9 members on one blog, it going to be really messy. Kobushi Factory's blog is already hectic with 8 members blogging. Good luck to the staff member in charge of monitoring their blogs.
I guess since they're still indies, their "seniority" status is just determined by age and the fact that some were placed in a year after will have nothing to do with it when they debut. Looking at the Mizuho/Kiki placement there.